Currently, numerous digital devices contain a user authentication apparatus, such as finger scanners that authenticate a user's identities by utilizing an image of the users fingerprint to match against a stored template fingerprint image and/or otherwise matching, e.g., utilizing fingerprint minutia extracted from such an image. Many such authentication devices are portable and battery powered. It is therefore essential that the power consumed by the operation of the authentication devices be kept to a minimum. What is needed, but has yet been provided, is a digital device that can contain an authentication device, such as a finger image scanner, which operates with minimal power consumption.
U.S. Pat. No. 8,278,946 B2, entitled APPARATUS AND METHOD FOR DETECTING FINGER ACTIVITY ON A FINGERPRINT SENSOR, issued on Oct. 2, 2012, and owned by the assignee of the present application discloses detection of bulk finger presence on or in the vicinity of the sensor elements. United States Pub. US2010/0180136A1 published on Jul. 15, 2010, entitled ULTRA LOW POWER WAKE-ON-EVENT MODE FOR BIOMETRIC SYSTEMS, and owned by the assignee of the present application discloses wake-on-event modes of operation for capacitive gap fingerprint sensors. United States Pub. US2010/0189314A1 published on Jul. 29, 2010, entitled LIVE FINGER DETECTION discloses bulk finger detection on or near capacitive gap fingerprint sensor elements.